YANGON, Myanmar—Myanmar’s government denied that security forces and a Buddhist mob attacked a village in an isolated corner of the country this past week and killed Muslim women and children. A rights group said more than a dozen people may have died and that hundreds of people have fled their homes.

The United States and Britain called on the government to investigate and to hold those responsible accountable.

“We have had no information about killings,” Deputy Information Minister Ye Htut told reporters Friday on the sidelines of a meeting of Southeast Asian foreign ministers in Myanmar’s ancient city of Bagan.

His comments were echoed by other government officials.

Myanmar, a predominantly Buddhist nation of 60 million people, has been grappling with sectarian violence for nearly two years. More than 240 people have been killed and another 250,000 forced to flee their homes, most of them Muslims from the western state of Rakhine.

The northern tip of the state, where Tuesday’s violence occurred, is home to 80 per cent of Myanmar’s Rohingya Muslims, considered by the United Nations to be one of the most persecuted minorities in the world. Foreign journalists cannot travel to the area and the work of humanitarian aid organizations is restricted.

Chris Lewa, director of the Thailand-based advocacy group Arakan Project, which has been documenting abuses against Rohingya for more than a decade, said details about the violence in Du Char Yar Tan village were still emerging, with many conflicting reports.

The death toll could be anywhere from 10 to 60, said Lewa, whose sources range from a village administrator to witnesses. One described the slashed-up bodies of three acquaintances—two women and a 14-year-old boy—found in their homes.

Some of the victims also were hit by bullets, the group was told.

Medecins Sans Frontieres, or Doctors Without Borders, which runs a nearby clinic, said it was concerned that residents who are in hiding may not be getting the medical care they need.

“MSF confirms that on Wednesday it saw two wounded people suffering from injuries inflicted as a result of violence—one from a gunshot wound and the other exhibiting injuries consistent with a beating,” said the group’s Myanmar head, Peter-Paul de Groote.

Tensions have been building in northern Rakhine since last month, when monks from a Buddhist extremist movement known as 969 arrived and started giving sermons by loudspeaker advocating the expulsion of all Rohingya.

One resident said by phone that the flare-up in Du Char Yar Tan village began following allegations by police that residents had abducted, and possibly killed, one of their officers, triggering a security crackdown.

Soldiers and police surrounded Du Char Yar Tan, breaking down doors and looting livestock and other valuables, said the man, who works as a volunteer English teacher. Worried they would be arrested, all the men fled, leaving the women, children and elderly behind, he said. He spoke on condition of anonymity because he feared reprisals.

That some of the victims appeared to have been stabbed with knives, not shot or beaten, “would clearly indicate the massacre was committed by (Buddhist) Rakhine villagers, rather than the police or army,” the Arakan Project wrote in a briefing Thursday.

The U.S. and Britain put out a joint statement Friday condemning the violence.

“We are particularly disturbed by reports that security forces used excessive means and thus perpetuated some of the violence,” the statement said, calling on Myanmar’s government to do more to address the root causes of ongoing violence, lawlessness and rights abuses in the state.

Ye Htut, the deputy information minister, said the reports of deaths this week “might be a coverup, because of the policeman going missing.”

Shwe Maung, a Muslim Lower House lawmaker who represents Buthidaung Township for the Union Solidarity and Development Party, told the local news agency Irrawaddy he had received conflicting reports about the numbers of casualties.

“A lot of people are missing,” he said. “Normally when they are missing family members, Rohingya people think they are dead.”

Some of the Rohingya in northern Rakhine descend from families that have been there for generations. Others arrived more recently from neighbouring Bangladesh. All have been denied citizenship, rendering them stateless.